Analysis of chiral non-steroidal anti-inflammatory drugs flurbiprofen, ketoprofen and etodolac binding with HSA

New look at the metabolism of nonsteroidal anti-inflammatory drugs: influence on human serum albumin antioxidant activity

Body's homeostasis is dependent on many factors, such as maintaining balance between free radicals formation and degradation. Human serum albumin (HSA) also plays an important role in homeostasis. The aim of this study was thermodynamic analysis of the interaction between ketoprofen (KET), naproxen (NPX), diclofenac (DIC) and HSA, as well as the effect of drug-albumin binding on HSA antioxidant activity using calorimetric and spectrophotometric techniques. Based on the calorimetric analysis it has been shown that accompanied by hydrophobic interaction drugs-albumin binding is an exoenergetic reaction. All analyzed drugs and HSA showed the ability to react with free radicals such as a radical cation, formed as a result of the reaction between 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) and potassium persulfate (K₂S₂O₈). Using ABTS assay a synergistic effect of ketoprofen (KET) and naproxen (NPX) on HSA antioxidant activity was observed while the effect of diclofenac (DIC) binding with albumin was probably additive. Because some medications including KET, NPX and DIC belong to over the counter (OTC) non-steroidal anti-inflammatory drugs (NSAIDs), it is necessary to understand their influence on HSA antioxidant activity.Communicated by Ramaswamy H. Sarma.

Study on the interaction of anti-inflammatory drugs with human serum albumin using molecular docking, quantitative structure-activity relationship, and fluorescence spectroscopy

The interaction of 14 anti-inflammatory drugs with human serum albumin (HSA) was investigated using fluorescence quenching, molecular docking studies, and quantitative structure-activity relationship (QSAR) methodology. Binding of anti-inflammatory drugs to HSA plays a fundamental role in their transport, distribution, delivery, and elimination. Binding constants of these drugs to HSA, obtained using the fluorescence quenching method, were within the range 0.01 × 10⁴  M^-1 (acetaminophen) to 1881.05 × 10⁴  M^-1 (meloxicam). Binding sites and binding constants of these anti-inflammatory drugs were estimated using molecular docking. Inspection of the obtained values for docking score, logK_b and K_b , showed that the drugs in this data set have a relatively strong binding constant for HSA. QSAR modelling was applied for binding constants obtained from fluorescence quenching and theoretical molecular descriptors. This modelling led to a linear two-parameter model with a correlation coefficient of 0.95 and adequate robustness. The descriptor results showed the importance of a bonding network and electronegativity as the discriminative structural factors in binding affinity for the HSA molecule.

Determination of the Lipophilicity of Ibuprofen, Naproxen, Ketoprofen, and Flurbiprofen with Thin-Layer Chromatography

The lipophilicity is an important parameter that influences the activity of the drugs in the human body. The reversed phase high performance thin layer chromatography was applied to determine the Log P values of ibuprofen, ketoprofen, naproxen, and flurbiprofen. The stationary phase used in the study was silica-gel coated plates. The mobile phase was the mixture of acetonitrile and water in different proportions. The content of acetonitrile varied in 5% increments from 50% to 80%. The Rm0 values were determined for the compounds with a known Log P and for the analyzed substances (ibuprofen, naproxen, ketoprofen, and flurbiprofen). The Log P values were calculated for the analyzed compounds using the regression curve Rm0 = f(Log P) parameters for the compounds with the known lipophilicity. Flurbiprofen is characterized by the highest Log P value: 3.82. The lowest one is noted for ketoprofen: 2.66. The determined Log P values of tested compounds were similar to the values calculated by the software.

Chiral pharmaceuticals: Environment sources, potential human health impacts, remediation technologies and future perspective

Chiral pharmaceuticals (CPs), including non-steroid anti-inflammatory drugs (NSAIDs), β-blockers and some herbicide and pesticides, are widely used in aquaculture, clinical treatment and many other fields. However, people are increasingly concerned about such ubiquitous pollutants, which can frequently be detected in contaminated soil and water. In large part, the significant sources of chiral pharmaceuticals stem from industrial processes, such as the direct discharge of untreated or incompletely treated wastewaters containing chiral pharmaceuticals, incorrect storage and use, animal wastes and biosolids. The main ways for human exposure to chiral pharmaceuticals are the disease treatment process and chiral pharmaceuticals contaminants. According to the results of a series of toxic studies, some diseases, even cancers, may be associated with exposure to certain chiral pharmaceuticals. Therefore, the treatment of chiral pharmaceuticals has become an important issue. The current advanced remediation techniques for chiral pharmaceuticals include the conventional method (sorption and sonolysis), biotransformation (an aerobic granular sludge-sequencing batch reactor and constructed wetland system) and advanced oxidation processes (ozonation and photocatalysis). Herein, in this review, we summarize the current status and sources of chiral pharmaceuticals, potential effects on human health, as well as the superiority, disadvantages and prospects of current advanced remediation technologies. Moreover, we also anticipate the prospect of the future research needed for chiral pharmaceuticals pollutant remediation.

Captopril/enalapril inhibit promiscuous esterase activity of carbonic anhydrase at micromolar concentrations: An in vitro study

The inhibitory activity of captopril, a thiol-containing competitive inhibitor of the angiotensin-converting enzyme, ACE, against esterase activity of carbonic anhydrase, CA was investigated. This small molecule, as well as enalapril, was selected in order to represents both thiol and carboxylate, as two well-known metal binding functional groups of metalloprotein inhibitors. Since captopril, has also been observed to inhibit other metalloenzymes such as tyrosinase and metallo-beta lactamase through binding to the catalytic metal ions and regarding CA as a zinc-containing metallo-enzyme, in the current study, we set out to determine whether captopril/enalapril inhibit CA esterase activity of the purified human CA II or not? Then, we revealed the inhibitors' potencies (IC₅₀, K_i and K_diss values) and also mode of inhibition. Our results also showed that enalapril is more potent CA inhibitor than captopril. Since enalapril represents no sulfhydryl moiety, thus carboxylate group may have a determinant role in inhibiting of CA esterase activity, the conclusion confirmed by molecular docking studies. Additionally, since CA inhibitory potencies of captopril/enalapril were much lower than those of classic sulfonamide drugs, the findings of the current study may explain why these drugs exhibit no effective CA inhibition at the concentrations reached in vivo and also may shed light on the way of generating new class of inhibitors that will discriminately inhibit various CA isoforms.

Stereoselective binding of chiral drugs to plasma proteins

Chiral drugs show distinct biochemical and pharmacological behaviors in the human body. The binding of chiral drugs to plasma proteins usually exhibits stereoselectivity, which has a far-reaching influence on their pharmacological activities and pharmacokinetic profiles. In this review, the stereoselective binding of chiral drugs to human serum albumin (HSA), α1-acid glycoprotein (AGP) and lipoprotein, three most important proteins in human plasma, are detailed. Furthermore, the application of AGP variants and recombinant fragments of HSA for studying enantiomer binding properties is also discussed. Apart from the stereoselectivity of enantiomer-protein binding, enantiomer-enantiomer interactions that may induce allosteric effects are also described. Additionally, the techniques and methods used to determine drug-protein binding parameters are briefly reviewed.

Analysis of species-dependent hydrolysis and protein binding of esmolol enantiomers

The stereoselective hydrolysis of esmolol in whole blood and in its separated components from rat, rabbit and human was investigated. Blood esterase activities were variable in different species in the order of rat>rabbit>human. Rat plasma showed the high esterase activity and had no stereoselectivity to enantiomers. Rabbit red blood cell (RBC) membrane, RBC cytosol and plasma all hydrolyzed esmolol but with different esterase activity, whereas the hydrolysis in RBC membrane and cytosol showed significant stereoselectivity towards R-(+)-esmolol. Esterase in RBC cytosol from human blood mainly contributed to the esmolol hydrolysis, which was demonstrated with no stereoselctivity. Esterase in human plasma showed a low activity, but a remarkable stereoselectivity with R-(+)-esmolol. In addition, the protein concentration affected the hydrolysis behavior of esmolol in RBC suspension. Protein binding of esmolol enantiomers in human plasma, human serum albumin (HSA) and α1-acid glycoprotein (AGP) revealed that there was a significant difference in bound fractions between two enantiomers, especially for AGP. Our results indicated that the stereoselective protein binding might play a role in the different hydrolysis rates of esmolol enantiomers in human plasma.

Stereoselective binding of mexiletine and ketoprofen enantiomers with human serum albumin domains

AIM

To investigate the stereoselective binding of mexiletine or ketoprofen enantiomers with different recombinant domains of human serum albumin (HSA).

METHODS

Three domains (HSA DOM I, II and III) were expressed in Pichia pastoris GS115 cells. Blue Sepharose 6 Fast Flow was employed to purify the recombinant HSA domains. The binding properties of the standard ligands, digitoxin, phenylbutazone and diazepam, and the chiral drugs to HSA domains were investigated using ultrafiltration. The concentrations of the standard ligands, ketoprofen and mexiletine were analyzed with HPLC.

RESULTS

The recombinant HSA domains were highly purified as shown by SDS-PAGE and Western blotting analyses. The standard HSA ligands digitoxin, phenylbutazone and diazepam selectively binds to DOM I, DOM II and DOM III, respectively. For the chiral drugs, R-ketoprofen showed a higher binding affinity toward DOM III than S-ketoprofen, whereas S-mexiletine bound to DOM II with a greater affinity than R-mexiletine.

CONCLUSION

The results demonstrate that HSA DOM III possesses the chiral recognition ability for the ketoprofen enantiomers, whereas HSA DOM II possesses that for the mexiletine enantiomers.